textproduct: Quad Cities

KEY MESSAGES

- A storm system(QLCS)may still be on track to propagate southeastward down across portions of the local area(more likely areas along/north of I-80)this morning and midday. Damaging wind is the still the primary risk, with a secondary risk of brief spin-up tornadoes. Much of the area remains in a Slight to Enhanced(levels 2 and 3 out of 5)Risk today. Strong to severe storms will be possible again on Wednesday.

- A Heat Advisory remains in effect for areas along/south of an Ottumwa, IA to Galesburg, IL line. Storm clouds and outflow may prevent it to be needed further north but it will still be very humid north of the advisory.

SHORT TERM /THROUGH TONIGHT/

Issued at 245 AM CDT Tue Aug 11 2026

The latest sfc analysis continues to indicate a west-to-east oriented quasi-stationary frontal boundary acrs central IA into northern IL, with rather light sfc flow going on around it making for another morning with patchy to areas of fog. Isolated to sctrd elevated WAA showers and a few thunderstorms are occurring north of the LLVL front acrs the north half of IA into WI even with a west-southwest veering H85 MB jet. Profiler network showing better southwesterly LLJ of 35-40 KTs converging on the MO RVR Valley, just to the lee of a seasonably robust short wave upper trof seen on water vapor imagery digging acrs eastern SD/southwest MN ATTM. This should be the region for MCS generation this morning, with a few storm clusters already occurring there.

Tightening CAPE and THTA-E gradient and prime H85 20C thermal ribbon align from southeast SD/ southwest MN down along to north of the local I-80 corridor through midday, and that's the currently expected path of an eventual MCS or QLCS type convective feature feeding on the LLJ jet that should be getting shunted this way ahead of the short wave as well as a mid level jet max. If this convective system can organize with a cold pool and mix along at least a 3000 J/kg MLCAPE pool at that time of morning, feel the already 70 KT+ wind gust potential could be there. Several of the latest CAM runs continue to target the highest wind gusts and bow apex along the Hwy 20 corridor and areas along the northern CWA border from around 10 am to noon or so. Some uncertainty on this, as a southwest tailing bow structure may also bring damaging winds down toward the I-80 corridor.

As this feature exit by early afternoon, it's cool pool outflow could very well shunt the main boundary further southward again with lingering convergence and diurnal heating help produce sctrd showers and a few thunderstorms in the wake of the main complex until the short wave can get by. Then would expect little convective activity by late afternoon and into the evening period as short wave ridging bulges overhead. Much of tonight may then be quiet until late toward dawn Wed when heights start to fall again and some LLVL jet convergence can maybe initiate some isolated showers and storms along or north of the southward shunted LLVL boundary acrs south central IA into the southern CWA. These may fester and last well into Wednesday with some severe risk if even somewhat elevated. Locally heavy rainfall and flooding may become more of a factor into Wed as well where the axis of storms can fire...right now it looks acrs the southern CWA.

As for the Heat Advisory, will let it ride and not expand it north with worries that this morning storms, debris and outflow will limit the ambient temps along and north of I-80 enough to fall short of advisory criteria. But it will still be oppressively humid, and if the MCS track further to the north than currently expected it may indeed need to be expanded north.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 245 AM CDT Tue Aug 11 2026

Wednesday...Talked a little bit about Wed above with some morning convection possible. But then it currently appears that the local area will lay in between the more organized forcing again for a potentially low activity period until maybe toward Thu morning when the next main short wave may be approaching. Also Wed will be another hot and humid day especially if convection is more scarce and can't rule out the eventual need of a heat headline for portions of the area.

Thursday through Monday...If the currently extrapolated short wave train along the edge of the heat dome is in the ballpark, we may have another MCS moving into the local area Thu morning with severe weather and heavy rain risks. The temperature battle will continue as well with LLVL baroclinicity and thermal ribbon wavering acrs the region for high heat or not so bad depending on the daily flux. Rainfall amounts may really add up by the weekend and early next week on the northern fringe of the heat dome from the west central plains, acrs IA/IL, and curving down acrs the eastern OH RVR Valley. Will have to watch the Thu through Friday period for heavy rain and back building MCS potential depending on LLVL boundary and convergent flow axis's lay out if long range 2 inch PWAT feed indicators are accurate.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1230 AM CDT Tue Aug 11 2026

For the rest of the overnight into dawn Tuesday, will have a mixture of VFR and MVFR stratocu north of I-80, as well as areas of fog to watch out for. A quasi-stationay west-to-east oriented sfc boundary will continue to waver acrs central IA into northern IL, with sfc winds light and variable along and just north of it, and southerly to southeast south of it. There may also be isolated high based showers or even a thunderstorm drifting along and north of the boundary in the VCNTY of CID and DBQ into Tue morning, bu the main storm show lurks upstream developing out of the Dakotas and southwest MN. This eventual MCS feature may sweep down as a line of severe storms with high end wind gusts feeding on the hot unstable air in place even at that time of day. How far north or south this feature propagates and what TAF sites get impacted are still uncertain, but for now have tried to time a couple hour TEMPO window at CID and DBQ the most likely sites to get hit by this storm complex. After that severe convection blows through, much of the rest of the TAF cycle may be VFR and benign in the wake.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Heat Advisory from noon today to 8 PM CDT this evening for IAZ087>089-098-099. IL...Heat Advisory from noon today to 8 PM CDT this evening for ILZ025-026-034-035. MO...Heat Advisory from noon today to 8 PM CDT this evening for MOZ009-010.